Low-melt polyester-based toners use a combination of amorphous and crystalline polyesters to achieve low-melt behavior, enabling faster print speeds and lower energy consumption. While the melting behavior of this polyester-based toner provides advantages over polystyrene-based chemical toners in print speed, fuser life, and energy consumption, the synthesis and emulsification of the polyester resin is much more time and energy-consuming. In particular, the preparation of polyesters by polycondensation takes several days and relies on high temperatures (T>190° C.) and low pressures (p<1 mmHg) to drive the polymerization to completion. In addition, the polycondensation reaction requires an organotin catalyst that cannot be removed from the resulting resin, remaining at non-negligible levels. This residual catalyst is carried through the toner-making process and eventually makes its way to the printed page, and later to recycling or disposal facilities. In summary, this production process is environmentally unfavorable.
The benefits of using enzymatic ring-opening polymerization of lactones at atmospheric pressure and relatively low temperatures to generate crystalline polyesters suitable for use in chemical toners is known in the art. However, this process is difficult to scale-up, as in a batch reaction, a large and costly quantity of supported enzyme catalysts are needed to maintain reasonable reaction rates. Recovery and recycling of the supported enzyme catalysts is therefore critical to such enzyme based technologies to ensure the economics as well as purity of the final product. However, recovering and recycling enzyme catalysts is not straight forward in processes where these enzyme catalysts are used to make large molecules (MW>2000) due to high product fluid viscosity. In order to recover the enzyme catalysts in these processes, a large quantity of solvent is used to lower the viscosity of the product fluid such that the catalyst settles out by gravity and/or centripetal acceleration. As a result, the scale-up of such a process is impractical as it is both environmentally taxing and economically challenging. For these reasons, there are no known processes for the production of commercially important polymers that rely on the recovery and recycling of supported enzyme catalysts.
Accordingly, there is a need to overcome these and other problems of prior art to provide a practical and environmentally benign method of producing polymers using the immobilized enzyme catalysts.